Power circuit breaker with arc quenching means



Dec. 19, 1967 H. MANZ 3,359,391

POWER CIRCUIT BREAKER WITH ARC QUENCHING MEANS Filed March 30, 1965 2Sheets-Sheet l ATTORNEYS".

Dec. 19, 1967 H. MANZ 3,359,391

POWER CIRCUIT BREAKER WITH ARC QUENCHING MEANS Filed March 30, 1965 2Sheets-Sheet 2 INVENTOR. //4/V$ MA/VZ United States Patent M 3,359,391POWER CIRCUIT BREAKER WITH ARC QUENCHING MEANS Hans Manz, Wallisellen,Switzerland, assignor to Maschinenfahrik ()erlikon, Zurich, SwitzerlandFiled Mar. 30, 1965, Ser. No. 443,784 Claims priority, applicationSwitzerland, Sept. 9, 1964,

1,793/ 64 6 Claims. (Cl. 200-150) ABSTRACT OF THE DISCLOSURE A powercircuit breaker is disclosed as including stationary and movablecontacts and an arc-control chamber containing a turbulator stack. Apiston is fixed to the movable contact and is movable within a pumpcylinder, this piston dividing the cylinder into a first compartmentbeneath the piston and a second compartment above the piston. Areservoir of quenching liquid communicates with the first compartmentand is communicable with the arc-control chamber through a non-returnvalve.

A liquid supply chamber containing the arc quenching liquid iscommunicable with the reservoir through a nonreturn valve, and a returnpath for quenching liquid extends between the arc-control chamber andthe liquid supply chamber.

During closing of the breaker contacts, quenching liquid is drawn fromthe supply chamber to the reservoir and the first compartment beneaththe piston and, during separation of the breaker contacts, quenchingliquid is forced out of the reservoir into the arc-control chamber andthrough the liquid return path back to the supply chamber.

Background of the invention This invention relates to power circuitbreakers of the type having an arc control chamber into which arequenching liquid is injected and, more particularly, to a novel powercircuit breaker of this type including novel means injecting a freshsupply of arc quenching liquid into the arc control chamber in eachoperation of the circuit breaker.

It is known, in power circuit breakers of the type having an'arc controlchamber into which are quenching liquid is injected during opening ofthe breaker contacts, to effect such injection by means of a pump pistonwhich is coupled to the movable breaker contact and movable therewith.Movement of the piston, during opening of the contacts, causes a jet ofquenching liquid to be directed along the length of the moving contactand against the fixed contact. A disadvantage of circuit breakers ofthis type is that there is little or no increase in the liquid pressurein the arc control chamber during opening of the breaker contacts. Toovercome this disadvantage, it has been proposed to assist quenching ofthe are by injecting quenching liquid under pressure into the arecontrol chamber from a separate source. However, this arrangement hasthe disadvantage of requiring a special pump for so injecting thequenching liquid into the arc control chamber.

An object of the present invention is to provide a power circuit breakerof the type having an arc control chamber into which quenching liquid isinjected by means 3,359,391 Patented Dec. 19, 1967 of a pump piston,during opening of the breaker contacts, and in which a fresh supply ofquenching liquid is injected into the arc control chamber during eachoperation cycle of the circuit breaker contacts.

Another object of the invention is to provide a power circuit breaker ofthe type having an arc control chamber into which arc quenching liquidis injected, during opening of the breaker contacts, by means of a pumppiston coupled to the movable breaker contact, and in which the pumppiston is associated with a reservoir into which quenching liquid isdrawn from a supply chamber during closing of the breaker contacts andquenching liquid is returned to the supply chamber during opening of thebreaker contacts and through the arc control chamber and a returnpassage connected to the supply chamber.

A further object of the invention is to provide a power circuit breakerof the mentioned type having means, including a pump connected between areservoir and the arc control chamber and having a liquid displacingelement coupled to the movable contact for movement therewith, thismeans being operable, during closing movement of the movable contact, toforce liquid under pressure into the control chamber and to draw liquidfrom the supply chamber into the reservoir.

Yet another object of the invention is to provide a power circuitbreaker of the type just mentioned, in which said means is operable,during opening movement of the movable contact, to force liquid from thereservoir into the control chamber and from the control chamber througha liquid return passage into the supply chamber.

Still another object of the invention is to provide a power circuitbreaker of the type mentioned including spring loaded valves interposedbetween the control chamber and the supply chamber, these valves beingnormally open and being designed to close when the liquid pressurewithin the control chamber exceeds a preselected value.

Still another object of the invention is to provide a power circuitbreaker of the type mentioned including novel means for protecting theinsulator of the circuit breaker from excessive loads.

A further object of the invention is to provide a power circuit breakerof the type mentioned, in which, if the pressure in the arc controlchamber increases to such an extent such that the valve connecting thereservoir to the arc control chamber cannot open, the liquid within thearc control chamber may escape through a clearance between a pump pistonand its cylinder and thereby blocking of contact opening movement of themovable contact is prevented.

For an understanding of the principles of the invention, reference ismade to the following description of a typical embodiment thereof, .asillustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a longitudinal sectional View of a circuit breaker embodyingthe invention, with the contacts being shown in their open position; and

FIG. 2 is a longitudinal sectional view of the circuit breaker shown inFIG. 1, and in a plane at a small angle to the plane of the longitudinalsection of FIG. 1, the contacts in FIG. 2 being illustrated during theirclosing movement; and

FIG. 3 is a somewhat schematic and enlarged perspective view of thecircuit breaker shown in FIGS. 1 and 2.

Referring to the drawings, a circuit breaker embodying the inventionincludes a lower compartment 1, constituting an arc quenching liquidsupply chamber which surmounts a supporting pedestal which is not shownin the drawings. Compartment 1 also houses a contact driving cylinder 2in which there is movable a piston 2a for operating the circuit breakercontacts.

The circuit breaker mechanism proper comprises essentially an arccontrol chamber 3 containing a turbulator stack 4, a relatively fixedcontact 5, and a movable contact or pin 6. The latter is actuated by thepiston 2a in the driving cylinder 2.

Movable contact or pin 6 forms the piston rod of a piston 7, which isslida-ble in a pump cylinder 8, and whose peripheral surface has arelatively small annular clearance 9 with the inner surface of thecylinder wall.

Piston 7 is fixedly connected to contact driving piston 2a,

and thus is movable by the latter and with the contact 6.

An insulator 10, surmounted by a cowl 11 and a cover 12, surrounds arccontrol chamber 3 and is separated therefrom by an annular space 13. Thelower end of annular space 13 is connected to are quenching fluid supplychamber 1 by a duct, or liquid return passage, 14. Compartment 1 andspace 13 are filled with the arc quenching liquid. The upper end ofannular space 13 is connected to the space within cowl 11, and thus toare control chamber 3, through the medium of normally open spring loadedvalves 15 and 16.

A reservoir 17 is operatively associated with cylinder 8 extendinglongitudinally of the latter. Reservoir 17 is in communication with thelower portion of cylinder 8, through an opening or port 18, is incommunication with are quenching liquid supply chamber 1 through a valve19, and is in communication with arc control chamber 3 through a valve20. A pipe or duct 21 extends longitudinally of reservoir 17 andprovides a connection between the upper end of cylinder 8, through themedium of an opening or port 22, and the supply chamber 1.

The circuit breaker operates in the following manner:

As stated, chamber or compartment 1 and annular space 13 are filled witharc quenching liquid. During closing movement of the circuit breakercontacts, in which movable contact 6 moves toward fixed contact 5,piston 7 moves upwardly in cylinder 8 and draws arc quenching liquidfrom supply chamber 1, through valve 19, reservoir 17, and opening 18,into cylinder 8 behind or beneath piston 7. During such upward movementof piston 7, the liquid above or ahead the piston is forced underpressure through opening 22 and, through pipe or duct 21, into supplychamber 1.

When contact 6 moves upwardly in arc control chamber 3, it temporarilycompresses the quenching liquid within chamber 3, Valve remains closed,and thus prevents liquid from escaping from arc control chamber 3 intoreservoir 17. The resulting increase in pressure in arc control chamber3 increases the electrical breakdown resistance and thus suppresses aclosing spark. During continued closing movement of contact 6, arequenching liquid flows through the slots in turbulator 4 and thencethrough a channel 23, cowl 11, and valves 15 and 16 into annular space13. Annular space 13 forms a liquid return passage or path leading tocompartment or supply chamber 1 through duct 14.

- During opening of the breaker contacts, when movable contact 6 movesdownwardly away from fixed'contact 5, piston 7 moves downwardly incylinder 8. Piston 7 thus forces the liquid beneath it in cylinder 8through port 18 into reservoir 17, and through valve 20 into arc controlchamber 3. This raises the pressure in arc control chamber 3 andproduces cross jets through the slots of turbulator 4, these cross jetsbeing considerably increased in intensity. From arc control chamber 3,the quenching liquid flows through channel 23 into cowl 11 and fromthere through valves 15 and 16 into space 13 between are control chamber3 and insulator 10. The liquid thus returns to supply chamber 1 throughduct 14.

As mentioned, valves 15 and 16 are spring loaded, and these valves arearranged to close when the liquid pres sure within cowl 11 and arecontrol chamber 3 exceeds a preselected value. Thus, should a shortcircuit current occur, resulting in the evolution of an excessivequantity of gas, the increased pressure will close valves 15 and 16,thus disconnecting space 13 from cowl 11. Insulator 10 is thus protectedfrom excessive loads.

As will be understood, liquid drawn into reservoir 17 from supplychamber 1 during closing of the breaker contacts, will be stored inreservoir 17 and injected into arc control chamber 3 during subsequentopening of contacts 5 and 6. Thus, the quenching liquid is circulatedand the same liquid is never used in arc control chamber 3 forconsecutive operations of the circuit breaker.

If a very high current, such as a short circuit current, is interruptedby the circuit breaker, the pressure in arc control chamber 3 may riseto such an extent that valve 20 is prevented from reliably opening. Insuch a case, part of the liquid can escape through the clearance 9during downward movement of piston 7, and thus prevent blocking of thedownward movement of the piston and opening of the contacts.

It will be apparent that an advantage of the present invention, asapplied to power circuit breakers of the type described, is that thevolume of quenching liquid can be kept to a minimum.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without depart-ing from such principles.

What is claimed:

1. A power circuit breaker comprising, in combination, an arc controlchamber containing a turbulator stack; a stationary contact within saidchamber; a movable con= tact engageable with and disengageable from saidsta= tionary contact; a pump cylinder; a piston fixed to said movablecontact and movable within said pump cylinder, said piston dividing saidpump cylinder into a firstbornpartment, beneath said piston, and asecond compart ment, above said piston; a reservoir communicating withsaid first compartment and communicable with said arc control chamber; afirst non-return valve controlling communication of said reservoir withsaid are control chamber; a supply chamber containing arc quenchingliquid and communicable with aid reservoir; a second non-return valvecontrolling communication of said supply chamber with said reservoir;and means defining a return path for quenching liquid extending betweensaid are control chamber and said supply chamber; the arrangement beingsuch that, during closing of the circuit breaker contacts, quenchingliquid is drawn from said supply chamber to said reservoir and saidfirst compartment and, during separation of the circuit breakercontacts, quenching liquid is forced out of said reservoir into said arecontrol chamber and through said liquid return path back to said supplychamber.

2. A power circuit breaker, as claimed in claim 1, including a portconnecting said first cylinder compartment to said reservoir.

3. A power circuit breaker, as claimed in claim 1, including a ductconnecting said second cylinder compartment to said supply chamber andextending through said reservoir.

4. A power circuit breaker, as claimed in claim 1, in which there is anannular clearance between said piston and the inner circumferentialsurface of said pump cylinder. 7

5. A power circuit breaker, asclaimed in claim 1, in which said arecontrol chamber is disposed within an insulator; the exterior lateralsurface of said are con- References Cited trol chamber and the interiorlateral surface of said UNITED STATES PATENTS insulator defining anannular space constituting said liquid 2,909,633 10/1959 Umphery 200 150return path.

6. A power circuit breaker, as claimed in claim 5, 5 FOREIGN PATENTSincluding pressure responsive valve means connecting said 1159538 2/1958France 1,330,551 5/1963 France. annular space to said arc controlchamber, said pressure 1,131,300 6/1962 Germany. responsive valve meanscloslng when the pressure m said arc control chamber exceeds apredetermined value. 10 ROBERT S. MACON, Primary Examiner.

1. A POWER CIRCUIT BREAKER COMPRISING, IN COMBINATION, AN ARC CONTROLCHAMBER CONTAINING A TURBULATOR STACK; A STATIONARY CONTACT WITHIN SAIDCHAMBER; A MOVABLE CONTACT ENGAGEABLE WITH AND DISENGAGEABLE FROM SAIDSTATIONARY CONTACT; A PUMP CYLINDER; A PISTON FIXED TO SAID MOVABLECONTACT AND MOVABLE WITHIN SAID PUMP CYLINDER, SAID PISTON DIVIDING SAIDPUMP CYLINDER INTO A FIRST COMPARTMENT, BENEATH SAID PISTON, AND ASECOND COMPARTMENT, ABOVE SAID PISTON; A RESERVOIR COMMUNICATING WITHSAID FIRST COMPARTMENT AND COMMUNICABLE WITH SAID ARC CONTROL CHAMBER; AFIRST NON-RETURN VALVE CONTROLLING COMMUNICATION OF SAID RESERVOIR WITHSAID ARC CONTROL CHAMBER; A SUPPLY CHAMBER CONTAINING ARC QUENCHINGLIQUID AND COMMUNICABLE WITH SAID RESERVOIR; A SECOND NON-RETURN VALVECONTROLLING COMMUNICATION OF SAID SUPPLY CHAMBER WITH SAID RESERVOIR;AND MEANS DEFINING A RETURN PATH FOR QUENCHING LIQUID EXTENDING BETWEENSAID ARC CONTROL CHAMBER AND SAID SUPPLY CHAMBER; THE ARRANGEMENT BEINGSUCH THAT, DURING CLOSING OF THE CIRCUIT BREAKER CONTACTS, QUENCHINGLIQUID IS DRAWN FROM SAID SUPPLY CHAMBER TO SAID RESERVOIR AND SAIDFIRST COMPART-MENT AND, DURING SEPARATION OF THE CIRCUIT BREAKERCONTACTS, QUENCHING LIQUID IS FORCED OUT OF SAID RESERVOIR INTO SAID ARCCONTROL CHAMBER AND THROUGH SAID LIQUID RETURN PATH BACK TO SAID SUPPLYCHAMBER.